I assumed John was pointing at verifying that perhaps the chemicals used in the production of the chair might have some really bad impact on the environmnet, start causing a problem with the food chain eco system and make food much scarcers for everyone—including the person who bought the chair—in the meaningfully near future. Something a long those lines.
As you note, verifying the chair functions as you want—as a place to sit that is comfortable—is pretty easy. Most of us probably do that without even really thinking about it. But will this chair “kill me” in the future is not so obvious or easy to assess.
I suspect at the core, this is a question about an assumption about evaluating a simple/non-complex world and doing so in an inherently complex world do doesn’t allow true separability in simple and independant structures.
That is certainly a more directly related, non-obvious aspect for verification. Thanks.